In 1974, Congress passed
the Safe Drinking Water Act. This law requires EPA to determine safe levels of
chemicals in drinking water which do or may cause health problems. These non-enforceable
levels, based solely on possible health risks and exposure, are called Maximum
Contaminant Level Goals.
The MCLG for toluene has been set at 1 parts per
million (ppm) because EPA believes this level of protection would not cause any
of the potential health problems described below.
Based on this MCLG, EPA
has set an enforceable standard called a Maximum Contaminant Level (MCL). MCLs
are set as close to the MCLGs as possible, considering the ability of public water
systems to detect and remove contaminants using suitable treatment technologies.
The MCL has also been set at 1 ppm because EPA believes, given present
technology and resources, this is the lowest level to which water systems can
reasonably be required to remove this contaminant should it occur in drinking
water.
These drinking water standards and the regulations for ensuring
these standards are met, are called National Primary Drinking Water Regulations.
All public water supplies must abide by these regulations.
What are
the Health Effects?
Short-term: EPA has found toluene to potentially
cause the following health effects when people are exposed to it at levels above
the MCL for relatively short periods of time: minor nervous system disorders such
as fatigue, nausea, weakness, confusion.
Long-term: Toluene has the potential
to cause the following effects from a lifetime exposure at levels above the MCL:
more pronounced nervous disorders such as spasms, tremors, impairment of speech,
hearing, vision, memory, coordination; liver and kidney damage.
How
much Toluene is produced and released to the environment?
Production
of toluene was 6.4 billion lbs in 1993. It is released into the atmosphere principally
from the volatilization of petroleum fuels and toluene-based solvents and thinners
and from motor vehicle exhaust. It is also released in wastewaters or by spills
on land during the storage, transport and disposal of fuels and oils.
From
1987 to 1993, according to EPA's Toxic Chemical Release Inventory, toluene releases
to land and water totalled over 4 million lbs., primarily from petroleum refining
industries. The largest releases occurred in Texas and California. The largest
releases directly to water occurred in Connecticut and West Virginia.
What
happens to Toluene when it is released to the environment?
Toluene
released to soil will be lost by evaporation from near-surface soil and by leaching
to the groundwater. Its breakdown by soil microbes is slow. Toluene evaporates
within a few hours when released to water, and it has little tendency to accumulate
in aquatic life.
How will Toluene be Detected in and Removed from My
Drinking Water?
The regulation for toluene became effective in 1992.
Between 1993 and 1995, EPA required your water supplier to collect water samples
every 3 months for one year and analyze them to find out if toluene is present
above 0.5 ppb. If it is present above this level, the system must continue to
monitor this contaminant.
If contaminant levels are found to be consistently
above the MCL, your water supplier must take steps to reduce the amount of toluene
so that it is consistently below that level. The following treatment methods have
been approved by EPA for removing toluene: Granular activated charcoal in combination
with Packed Tower Aeration.
How will I know if Toluene is in my drinking
water?
If the levels of toluene exceed the MCL, 1 ppm, the system must
notify the public via newspapers, radio, TV and other means. Additional actions,
such as providing alternative drinking water supplies, may be required to prevent
serious risks to public health.
Drinking Water Standards:
Mclg:
1 ppm
Mcl: 1 ppm
Toluene Releases to Water and Land, 1987 to 1993
(in pounds):
=
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